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History of the Holocene
See also: Timeline of the Holocene The Holocene is the current . It began approximately 11,650 years , after the , which concluded with the . The Holocene and the preceding together form the period. The Holocene has been identified with the current warm period, known as . It is considered by some to be an period within the Pleistocene Epoch. The Holocene has seen the growth and impacts of the human species worldwide, including , development of major civilizations, and overall significant transition towards urban living in the present. Human impacts on modern-era and its s may be considered of global significance for future evolution of living species, including approximately synchronous evidence, or more recently and evidence of human impacts. In July 2018, the split the Holocene epoch into three distinct subsections, (11,700 years ago to 8,326 years ago), (8,326 years ago to 4,200 years ago) and (4,200 years ago to the present), as proposed by . The boundary of is a in in India, and the global auxiliary stratotype is an from in Canada. The name Holocene comes from the words (holos, whole or entire) and (kainos, new), meaning "entirely recent". Overview It is accepted by the that the Holocene started approximately 11,650 years . The Subcommission on Quaternary Stratigraphy quotes Gibbard and van Kolfschoten in Gradstein Ogg and Smith in stating the term 'Recent' as an alternative to Holocene is invalid and should not be used and also observe that the term Flandrian, derived from marine transgression sediments on the Flanders coast of Belgium has been used as a synonym for Holocene by authors who consider the last 10,000 years should have the same stage-status as previous interglacial events and thus be included in the Pleistocene. The , however, considers the Holocene an epoch following the and specifically the . Local names for the last glacial period include the in North America, the in Europe, the Devensian in Britain, the in Chile and the Otiran in New Zealand. The Holocene can be subdivided into five time intervals, or s, based on climatic fluctuations: * (10 ka–9 ka BP), * (9 ka–8 ka BP), * (8 ka–5 ka BP), * (5 ka–2.5 ka BP) and * (2.5 ka BP–present). : Note: " " means "kilo-annum" , i.e. 1,000 years before 1950 (non-calibrated ) , according to .}} The of climatic periods initially defined by plant remains in es, is currently being explored. Geologists working in different regions are studying sea levels, peat bogs and ice core samples by a variety of methods, with a view toward further verifying and refining the Blytt–Sernander sequence. They find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for , but the s were claimed to occur more widely. The periods of the scheme include a few of the final pre-Holocene oscillations of the last glacial period and then classify climates of more recent . have not defined any s for the Holocene. If subdivision is necessary, periods of human technological development, such as the , , and , are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world. Climatically, the Holocene may be divided evenly into the and periods; the boundary coincides with the start of the in Europe. According to some scholars, a third division, the , has now begun. The International Commission on Stratigraphy Subcommission on Quaternary Stratigraphy's working group on the 'Anthropocene' (a term coined by Paul Crutzen and Eugene Stoermer in 2000) note this term is used to denote the present time interval in which many geologically significant conditions and processes have been profoundly altered by human activities. The 'Anthropocene' is not a formally defined geological unit. Geology on near }} Continental motions due to are less than a kilometre over a span of only 10,000 years. However, ice melt caused world about in the early part of the Holocene. In addition, many areas above about latitude had been depressed by the weight of the Pleistocene glaciers and rose as much as due to over the late Pleistocene and Holocene, and are still rising today. The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea. Holocene marine fossils are known, for example, from and . Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found primarily in lakebed, floodplain, and cave deposits. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely of non-glacial origin. Post-glacial rebound in the region resulted in the formation of the . Earthquakes are a leading cause of sediment deformation, leading to the creation and destruction of bodies of water. The region continues to rise, still causing weak s across . The equivalent event in was the rebound of , as it shrank from its larger, immediate post-glacial phase, to near its present boundaries. Climate approximately 9,000 years ago during the early Holocene and after the end of the .}} Climate has been fairly stable over the Holocene. records show that before the Holocene there was global warming after the end of the and cooling periods, but climate changes became more regional at the start of the . During the transition from the last glacial to the Holocene, the in the began before the Younger Dryas, and the maximum warmth flowed south to north from 11,000 to 7,000 years ago. It appears that this was influenced by the residual glacial ice remaining in the until the later date. The (HCO) was a period of warming in which the global climate became warmer. However, the warming was probably not uniform across the world. This period of warmth ended about 5,500 years ago with the descent into the and concomitant . At that time, the climate was not unlike today's, but there was a slightly warmer period from the 10th–14th centuries known as the . This was followed by the , from the 13th or 14th century to the mid-19th century. Compared to glacial conditions, habitable zones have expanded northwards, reaching their northernmost point during the HCO. Greater moisture in the polar regions has caused the disappearance of . The temporal and spatial extent of Holocene climate change is an area of considerable uncertainty, with recently proposed to be the origin of cycles identified in the North Atlantic region. Climate cyclicity through the Holocene ( ) has been observed in or near marine settings and is strongly controlled by glacial input to the North Atlantic. Periodicities of ˜2500, ˜1500, and ˜1000 years are generally observed in the North Atlantic. At the same time spectral analyses of the continental record, which is remote from oceanic influence, reveal persistent periodicities of 1,000 and 500 years that may correspond to solar activity variations during the Holocene epoch. A 1,500-year cycle corresponding to the North Atlantic oceanic circulation may have had widespread global distribution in the Late Holocene. Ecological developments Animal and plant life have not evolved much during the relatively short Holocene, but there have been major shifts in the distributions of plants and animals. A including s and s, s like and , and s disappeared in the late Pleistocene and early Holocene—especially in North America, where animals that survived elsewhere (including horses and camels) became extinct. This extinction of American has been explained as caused by the arrival of the ancestors of s; though most scientists assert that climatic change also contributed. In addition, a controversial over North America has been hypothesized to have triggered the . Throughout the world, ecosystems in cooler climates that were previously regional have been isolated in higher altitude ecological "islands". The , an abrupt cold spell recorded as a negative excursion in the record lasting 400 years, is the most prominent climatic event occurring in the Holocene epoch, and may have marked a resurgence of ice cover. It has been suggested that this event was caused by the final drainage of , which had been confined by the glaciers, disrupting the circulation of the . Subsequent research, however, suggested that the discharge was probably superimposed upon a longer episode of cooler climate lasting up to 600 years and observed that the extent of the area affected was unclear. References Category:History of the world